In the context of the recent invention, the term “client system” is understood to mean a system which is fitted in an aircraft and which comprises functions able to be triggered by said dialogue device, under the action of the operator, for the purpose of their execution. Moreover, the term “execution of a function, in understood to mean, in particular:                implementation of a control of an element (engine, lighting, etc) of the aircraft or of a particular action;        entry of data;        access to information pages on screens; and/or        access to information or complementary actions without changing the page.        
Although not exclusively, a client system can correspond in particular to an FMS (“Flight Management System”), to a tactical management system or to a monitoring system.
Said dialogue device which is installed in the aircraft usually comprises:                a display system comprising at least one screen which is able to display at least one interactive window. In the context of the present invention, this interactive window comprises a plurality of layers, each of which is associated with one of said client systems, each of said client systems being associated with a single layer of the interactive window. Moreover, each of said layers comprises at least one interactive object able to display a menu which is intended for the system associated with said layer; and        at least one cursor control device which is able to be actuated manually by said operator and which comprises:                    at least one movement means which can be actuated, for example a rotary knob or a mouse, able to move a cursor over said interactive window in such a way as to indicate an interactive object; and            at least one validating means which can be actuated, able to validate an interactive object which is indicated by the intermediary of said cursor in order to open the corresponding menu.                        
When an operator, in particular the pilot of the aircraft, wishes to interact with an interactive object, for example in order to move a waypoint of the aircraft's flight plan, he must place the cursor on that interactive object with the help of said movement means which can be actuated, and he must then validate the latter using said validation means which can be actuated. In response to this validation, the menu corresponding to that interactive object is opened, which generally makes it possible to offer the pilot a choice of actions to take. The pilot can then continue the interactivity by clicking on the line of the menu corresponding to the function he wishes to activate, for example the movement of a waypoint of the flight plan.
Such a display on a screen using a plurality of layers associated with different client systems makes it possible for several interactive objects to be displayed simultaneously at the same position on the screen, if they are positioned at latitudes and longitudes that are identical or very close to each other. In this case, if the operator brings the cursor to such a position on the screen where there are several interactive objects corresponding to different layers and if he validates this position of the cursor, the applications of the corresponding client systems will each at the same time open a menu corresponding to the interactive object thus validated. Such an opening of a plurality of different menus will result in a masking of a large portion of the screen, whereas the pilot simply wishes to interact with a single and particular interactive object. Such a multiple opening obviously complicates the pilot's comprehension and reading of the display and increases his workload.